Apparatus for form-frying snack food product

ABSTRACT

Apparatus and method for cooking snack food pieces features a drum-type fryer which transports individual, die-cut piece preforms through hot oil contained within a cooking tank defined between the periphery of the drum and a housing in which the drum is contained. Vacuum transfer and feed rollers transfer the individual piece preforms from a die-cutting roller assembly onto the drum for cooking, and a similar roller transfers the cooked snack food pieces from the drum to a take-away conveyor for subsequent, downstream processing. The pieces are retained by suction against molding surfaces of frying mold elements distributed over the periphery of the frying drum.

This is a divisional application of application Ser. No. 09/556,695,filed Apr. 24, 2000 now U.S. Pat. No. 6,412,399.

FIELD OF THE INVENTION

In general, the invention relates to an apparatus and method for makingfabricated snack food products such as potato crisps or tortilla chips.More particularly, the invention relates to an apparatus and method forform-frying such products.

BACKGROUND OF THE INVENTION

In general, snack food chips which are made from potato, corn, or otherfarinaceous dough and which are formed or fabricated such that the chipsall have the same shape and/or configuration are known in the art.Packaging fabricated snack food chips in a stacked arrangement incylindrical canisters is also known in the art and has been found to bepopular for a number of reasons. Such canisters provide some degree ofprotection against breakage of the snack food chips, and they providegreater transportability of the snack food product, both in terms ofbulk transport (i.e., large cartons of the canisters being shipped,e.g., from the manufacturer to the retailer) and in terms of theindividual consumer being able to transport a single package of chips(e.g., in a purse or in a picnic basket). Additionally, the extendedshelf life of a sealed canister of snack food chips as compared to a bag(commonly pillow-shaped and sometimes filled with a generally inert gasto prevent product degradation), as well as the ability to seal acanister with a snap-fit-type lid once the canister has been opened,makes a canister a particularly attractive packaging option.

In order to manufacture and package form-fried snack food chipsefficiently, it is necessary to maintain control over the productconfiguration and arrangement throughout the fabrication process. In thepast, this requirement has been met by using enclosed molds to shape orform the snack chips and to restrain them as they are transportedthrough a cooking medium such as hot oil. However, not only is such anapparatus complex and therefore relatively prone to mechanical failure,but the complexity limits how close together the chips can be arrangedin the production line and therefore limits the productivity of theapparatus. Additionally, the volume of oil or other cooking medium usedwith such apparatus also tends to be relatively large. Accordingly, thecost of operating the system is generally higher than would be desired.

SUMMARY OF THE INVENTION

The invention provides an apparatus and method for making fabricatedsnack food chips which are uniformly shaped and configured. Theapparatus is compact and elegantly simple in design and overcomes theabove-noted shortcomings extant in the prior art apparatus andmethodologies.

In particular, the invention features a drum-type frying apparatus whichtransports snack food chip preforms through a relatively small volume ofhot oil that is contained within a space formed between the drum and thesurrounding wall of a housing in which the drum is supported. The drumhas perforated mold elements disposed around its periphery, and the chippreforms are supported on the mold elements by drawing suction throughthe perforations.

A series of vacuum rollers transfer the uncooked chip preforms from acutter roller assembly onto the mold elements using perforated pick-upand transfer members arranged around the perimeters of the vacuumrollers. Similarly, a take-off roller uses perforated pick-up andtransfer members disposed around its perimeter to remove the cookedchips from the fryer drum. The cooked snack food chips are then removedfrom the take-off roller and transported downstream for subsequentprocessing (light re-oiling and seasoning) and packaging (e.g., incanisters, which may preferably conform to the contour or perimeter ofthe cooked chips).

The inventive apparatus and method allow one to produce form-fried snackfood chips which are uniform in shape and configuration quickly andconveniently and with enhanced process control. Additionally, the amountof oil used in the process is minimized. Because relatively less oil ispresent in the apparatus at any given time as compared to prior artapparatus, the oil is used and replenished or “turned over” morefrequently, and therefore the oil quality remains high.

Furthermore, and quite significantly, the configuration of the apparatusminimizes exposure of the oil to the ambient atmosphere. This is becausewhereas the two-piece prior art enclosed mold cavities presentedmultiple surfaces over which the oil could spread in the form of a film,thus creating a large oil surface area which could oxidize when exposedto the ambient air, the present invention utilizes just a single moldsurface to shape the snack food product, thereby minimizing the amountof oil (in the form of an oil film spread over the metal surfaces) thatis exposed to the atmosphere and that is susceptible to degradingoxidation. Additionally, the apparatus of the invention preferablyincludes means for controlling the nature of the atmosphere to which theoil is exposed. In particular, the portion of the apparatus where thesnack food chips enter the fryer and are removed from the fryerpreferably is shrouded, and an gas such as carbon dioxide or nitrogen isinjected into the shrouded area to minimize exposure of the oil tooxygen. These features of the invention significantly improve thequality of the snack food chips produced by the system.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in greater detail in connection withthe drawings, in which:

FIG. 1 is a schematic, side elevation view showing the fryer apparatusof the invention;

FIGS. 2A-2D are schematic side elevation, end, and perspective viewsshowing the fryer mold elements used in connection with the apparatus ofthe invention;

FIG. 2E is a schematic perspective view showing an alternateconfiguration of the fryer mold elements used in connection with theapparatus of the invention;

FIG. 3 is a bottom view taken along the lines 3—3 in FIG. 2A;

FIG. 4 is a schematic diagram illustrating the system for creatingsuction within the fryer drum of the invention;

FIG. 5 is a schematic, side elevation view showing the cutter, feed, andtake-off roller system located at the top of the apparatus in FIG. 1 ingreater detail;

FIG. 6 is a schematic, side elevation view showing the transfer rollerand feed roller shown in FIG. 5 in greater detail;

FIG. 7 is a section view of a pick-up and transfer member used on therollers shown in FIG. 6 taken along the lines 7—7 therein;

FIG. 8 is a schematic depiction of a preferred cutting pattern used tomake form-fried potato crisps according to the invention;

FIG. 9 is a section view, similar to the section view of FIG. 7,illustrating the pick-up and transfer members used on the take-offroller; and

FIGS. 10-12 are two schematic perspective views and a schematic,side-elevation view illustrating removal of cooked snack food chips fromthe frying apparatus of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

A preferred embodiment of a drum-type fryer apparatus 10 according tothe invention is shown in FIG. 1. The “heart” of the apparatus is thedrum 12, which is rotationally supported in a substantially enclosedcylindrical tank or chamber 14 defined between the drum 12 and theinterior wall of a housing 16. A steam jacket 15 surrounds the tank andis used to keep oil in the tank 14 hot. End walls (not shown) aresecured to the housing over the ends of the drum 12 so as to enclosesubstantially the tank or chamber 14, leaving it open only over thearcuate segment 20 along the upper portion thereof. Shrouding S isprovided over the tank entrance/exit portion of the fryer, and inert gassuch as nitrogen or carbon dioxide is injected through injection ports(not shown) into the shroud-enclosed regions of the apparatus to reduceexposure of the oil to the oil-degrading oxygen in the ambientatmosphere.

The drum has an outer ring 22 to which a large multiplicity (i.e., onthe order of six thousand for commercial scale production) of fryingmold elements are secured. As shown in FIGS. 2A-2D, each frying moldelement 26 has an upper, mold portion 28 and a supporting stem portion30 to which the mold portion 28 is joined by press fit engagement ormeans such as laser welding. Both portions of the frying mold elements26 are fabricated from material such as stainless steel, aluminum, orother metals which can withstand the high temperature of the cooking oil(i.e., on the order of 340-400EF). A high efficiency of thermalconductivity of the frying mold elements is important for cooking thechips thoroughly. In certain cases, the mold elements may utilize an ionconversion coating to facilitate release of the cooked chips therefrom.

Each mold portion 28 is fabricated such that its upper, molding surface32 has a desired contour which will impart to the finished snack foodchip the same contour. In the exemplary embodiment shown in the figures,the molding surface 32 is saddle-shaped with convex curvature about afirst axis oriented in one direction and concave curvature about asecond axis oriented perpendicular to the first axis. Alternatively, themolding surfaces 32 might be curved about just a single axis ofcurvature.

The stem portions 30 of the frying mold elements are each formed as ahollow cylinder which fits into an aperture 34 in the outer ring 22.Preferably, the frying mold elements 26 are configured to “snap” intoposition in the apertures 34 and to be held securely therein by means ofretention fingers 36 and retention lugs 38 at the ends of the retentionfingers. As the stem portions 30 of the frying mold elements areinserted into the apertures 34, the chamfered cam surfaces 40 of theretention lugs 38 will contact the edges 42 of the apertures 34 andforce the retention fingers 36 inwardly. When the frying mold elementsare properly seated, the retention fingers 36 will snap back into theiroriginal positions and engage shoulders 44 formed in the surfaces of theapertures, near the interior ends of the apertures to secure the fryingmold element in place.

Preferably, the frying mold elements have break-away positioning tabs 46which fit within slots (not shown) in the walls of the apertures 34 or,alternatively, in holes (not shown) in the surface 48 of the outer ring22. This feature orients the frying mold elements properly within theapertures 34.

The apertures 34 also have beveled or cammed slide-out ramps 50 formedon their inner surfaces, with a slide-out ramp 50 provided for eachretention finger/retention lug. (See FIGS. 2A and 3.) The frying moldelements can be removed from the outer ring 22, e.g., to be replaced orwhen it is desired to change to a different product configuration, bytwisting them within the apertures with sufficient force to break offthe positioning tabs 46. The cam surfaces 40 of the retention lugs willthen slide against the cam surfaces 52 of the slide-out ramps 50 and theretention fingers 36 will be depressed inwardly. The retention lugs 38thus will be moved out of engagement with the shoulder surfaces 44, andthe frying mold elements can be removed from the apertures 34.

As further shown in FIGS. 2A-2C, each of the mold surfaces 32 isperforated, as indicated by stippling. By creating suction within thehollow interiors of the frying mold elements 26 via vacuum manifoldsystem 19 as addressed below, the snack food chip preforms are pulledagainst the mold surfaces 32 by suction forces and transported throughhot oil in the tank 14. The perforations should be small enough toprevent dough from accumulating in them, but large enough to draw asufficiently strong vacuum through them to retain the chips.

The mold surfaces 32 also have a series of channels or grooves 60 formedtherein. Thus, the mold surfaces 32 will have a desired texture; thattexture is imparted to the snack food chips by virtue of the chippreforms being pulled against the mold surfaces 32 by the suctionforces, and that texture enhances the “mouth feel” of the chips and addsstrength to the chips. Significantly, the grooves or channels 60 alsofacilitate the circulation of oil around the chips—particularly acrossthe surfaces of the chips that are adjacent to the mold surfaces32—thereby providing more uniform cooking of the chips. Moreover, as theoil circulates through the grooves 60, steam (formed from moisturereleased by the snack food product as it is fried) which has mixed withthe oil is drawn off by the suction forces used to hold the chipsagainst the mold surfaces. This helps to reduce the necessary totalcooking time, since the relative amount of oil (which is hotter than thesteam) to which the chips are exposed is increased, and thus the rate ofproduct throughput can be increased.

Furthermore, the surface texture can be specifically tailored tofacilitate release and removal of the cooked chips from the moldsurfaces 32 by, for example, providing grooves or channels which allextend in the same direction and/or by controlling the depth and spacingof the grooves or channels. (This concept can be extended to making thechannels deep enough and wide enough to produce a ridged or sinusoidally“wavy” chip.) The mold elements may be changed simply to change thetexture of the final product, if so desired.

An alternate configuration of a frying mold element 26′ is shown in FIG.2E. In this configuration, the frying mold element includes an upper,mold portion 28′ and a lower, base portion 28″ to which the mold portion28′ is connected. The base portion 28″ has a number of spring releasefingers 31—preferably two on either side of the element 26′—extendingupward from it. Each of the spring release fingers 31 has a circularlocking tab 33 at its end. The upper, mold portion 28′ is generallyhollow and fits down over the spring release fingers, with the springrelease fingers located in the interior of the mold portion as indicatedby the dashed line depiction of the spring release fingers. The lockingtabs 33 engage apertures 35 formed in the sidewalls of the mold portion28′ to secure the mold portion 28′ to the base portion 28″. The moldportion 28′ can be changed quite easily by pressing in on the lockingtabs to release the mold portion and simply lifting the mold portion offof the base portion.

With this configuration, the supporting stem portion 30′ can be simplerthan in the preceding configuration. For example, it may be formed witha slight amount of taper and secured to the outer ring 22 of the drum 12by being press-fit into the cylindrical apertures 34. (See FIG. 2A.)

Referring back to FIG. 1, the outer ring 22 is supported on theperimeter of the drum 12, and the apparatus is configured such that themain body of the drum remains stationary and the outer ring 22 rotatesaround it with the frying mold elements 26 secured thereto. The interiorof the drum includes a manifold system 19. The manifold system is usedto maintain a relatively constant level of force against the chips asthey rotate through the tank 14, regardless of their rotational positionwithin the tank. In particular, it will be appreciated that thehydraulic pressure of the oil (which is injected into the tank 14 viainlet weir 64 and drawn out of the tank via outlet weir/filter 66) willbe higher at the bottom of the tank, in the region of oil sump 68, thannear the top of the tank. In a commercial-scale installation, forexample, in which the drum will be on the order of fourteen feet indiameter and six feet wide (depending on desired product throughput),the oil pressure at the bottom of the tank (e.g., in the sump 68) willbe on the order of five or six psi.

It is preferable for the pressure differential across the chip to remainrelatively constant through the frying process (preferably on the orderof a pressure head equivalent to ten inches of water (0.36 psi)) so asto prevent the pressure from pushing the soft chip preforms into theperforations and grooves in the mold surfaces 32. Therefore, themanifold system consists of a number of smaller suction cells orchambers 70 which extend from one end of the drum 12 to the oppositeend. A system of valves or pressure reducers (not shown) is used tocontrol the level of suction being drawn through each of the individualcells 70 such that the net pressure differential across the chip remainsrelatively constant at the desired value, i.e. ten inches of water.Thus, more suction will be drawn in the cells 70 near the upper portionof the apparatus than in the cells 70 near the lower portion of theapparatus because, near the bottom of the apparatus, the weight-inducedpressure of the oil itself will help to keep the snack food chippreforms secured against the molding surfaces 32.

As illustrated in FIG. 4, suction is created within the manifold system19 by means of a blower 74. As air is drawn out of the vacuum plenum bymeans of the blower, oil which has been pulled through the perforationsin the mold surfaces 32 (either by circulating around the snack foodchips or by being pulled through the pores of the snack food chips,which enhances cooking) will be pulled out of the vacuum plenum as well.Additionally, steam produced from moisture released by the snack foodchips during the frying process will also be drawn out of the plenum.Accordingly, a separator 76 is provided to remove oil and steam from theair being drawn out of the plenum 18; the oil is collected, filtered,and then recycled.

The frying apparatus 10 further includes a system 82 of cutter,transfer, feed, and take-off rollers. As shown in FIG. 5, the system 82includes sheeter rollers 84, 86 and cutter roller 88, which may berelatively conventional in construction. For making stackable,fabricated potato chips, the cutter roller preferably produces a cuttingpattern as shown in FIG. 8. Notably, because the drum-type fryerassembly of the invention is so simple in construction and does not relyon complex two-piece molds to restrain the snack food chips as they aretransported through the oil, the chips can be cut from the sheet ofdough in the relatively tightly packed or “nested” configuration shownin FIG. 8. (Other shaped snack food products may also be made using theapparatus and method of the invention, and the configuration of thecutter roller will vary accordingly.)

The system of rollers 82 further includes an intermediate transferroller 100 and a feed roller 102. As shown in greater detail in FIGS. 6and 7, each of these rollers is constructed with an outer ring 104, 106,respectively, with a large multiplicity of pick-up and transfer members105, 107, respectively, disposed thereon. The outer rings 104, 106rotate in the directions indicated by the arcuate arrows (FIG. 5) aroundvacuum/over-pressure drums 108, 110, respectively. The drums 108 and 110are constructed with blowers and manifold systems (not shown) configuredto create suction in the sectors indicated by stippling andover-pressure in the sectors indicated by cross-hatching.

As shown in greater detail in FIG. 7, each of the pick-up and transfermembers 105, 107 consists of a generally mushroom-shaped element whichis secured by means of a press fit in an aperture 112 in the outer ring104 or 106. Each of the members 105 or 107 is fabricated from a hollowsupport stem 120 and a silicone rubber picker pad 122. The picker pad122 fits over the open upper end 124 of the stem 120 and is retainedthereon by means of a lip 126 at the upper end of the stem, which lipmates with a groove 128 formed on the inside surface of the picker pad122. The picker pad preferably is sized for a stretch fit over the openend of the stem 120. Furthermore, as indicated in FIG. 7, it ispreferable for the portion of the picker pad which fits over the end ofthe stem to be harder than the upper or distal-most portion of thepicker pad. For example, the portion 130 preferably has a hardness valueof 70-80 durometer, whereas the upper portion 132 preferably has ahardness value on the order of 15 durometer. This configuration providesthe strength necessary to keep the picker pads secured to the stems 120while permitting the picker pads to flex slightly as they transfer thesnack food chips from one roller to another, as described in greaterdetail below.

As further indicated in FIG. 7, the upper portions 132 of the pickerpads have perforations 136 extending through them. The perforations areprovided such that the vacuum created within the stippled sectors of therollers 100, 102 and the over-pressure created within the cross-hatchedsectors will be transmitted through the picker pads to cause the snackfood chip preforms to adhere to the pick-up members or be blown off ofthe pick-up members at the appropriate times, as described in greaterdetail below in connection with operation of the apparatus.

Finally, with respect to the pick-up and transfer members of thetransfer roller 100 and the feed roller 102, it will be appreciated thatthe snack food chip preforms will be almost completely flat (i.e., withjust a slight amount of curvature due to the curvature of the cutterroller 88) at the nip 140 where the transfer roller 100 picks thepreforms off of the cutter roller 88, whereas the mold surfaces 32 ofthe frying mold elements 26 are far more curved. Accordingly, thepick-up and transfer members 105, 107 are configured to stretch the chippreforms gradually and progressively to have the desired shape at thetime they are deposited onto the frying mold elements 26. This givesbetter shape to the chips and prevents the dough from being torn, whichwould be more likely if the dough were stretched into the final productshape all in one step. The picker pads on the rollers 100, 102 are ofcomplimentary or mating configuration and fit together to provide forsecure, positive transfer from one roller to the next; the picker padsof the feed roller 102 are similarly complimentarily configured to matewith the mold surfaces 32 to provide positive transfer from the feedroller onto the fryer drum.

The system 82 further includes a pick-off roller 150 which is used toremove cooked snack food chips from the fryer drum, and a transferconveyor assembly 160 (FIGS. 10-12) which features finger conveyors toremove the cooked snack food chips from the pick-off roller 150 andtransfer them downstream for subsequent processing.

The pick-off roller 150 is constructed generally similarly to thetransfer roller 100 and feed roller 102 in that it includes an outerring 151 which rotates relative to a vacuum drum 153, and pick-up andtransfer members 152 secured thereto. The pick-up and transfer members152 are constructed generally similarly to the pick-up members 105, 107on the transfer roller and feed roller 102, respectively, in that theyare generally hollow and have apertures formed through picker padsdisposed on their upper ends to transmit suction forces to the cookedsnack food chips which have been retrieved from the fryer drum by theroller 150. As shown in FIG. 9, however, the pick-up and transfermembers 152 are narrower than the pick-up and transfer members on thetransfer and feed rollers 100, 102. This allows the fingers 162 of thetransfer conveyor assembly 160 to fit between the pick-up and transfermembers 152, as illustrated in FIGS. 10 and 12. Additionally, the drumof the pick-off roller 150 has a sector, indicated by stippling, whichextends from the bottom portion of the roller to slightly past the topportion of the roller. This configuration permits the pick-off roller150 to pick the cooked snack food chips off of the fryer drum locatedbelow it and transfer them to the fingers 162 of the take-away conveyorapparatus.

Finally, with respect to the roller system 82, the various rollers aremounted on arms 180 and 182 which pivot around pivot points 184 and 186,respectively. Cam followers 188, 190 are attached at the free ends ofthe arms 180, 182 and follow the perimeter of the fryer drum to ensureproper positioning of the various rollers.

The apparatus of the invention operates as follows. Dough (e.g. afarinaceous dough such as potato dough or corn dough) is fed to thesheeter rollers 84, 86 through slot 90 in the housing 92. The sheeterrollers form the dough into a sheet which adheres to the lower portionof the roller 86 as it rotates. The dough sheet is then cut intoappropriately shaped snack food chip preforms by the cutter roller 88.

The die-cut sheet of dough is carried over the top of the cutter roller88, and the die-cut chip preforms are picked off of the cutter roller 88by the pick-up and transfer members 105 of the transfer roller 100.Suction created within the portion of the drum 108 indicated bystippling (FIGS. 5 and 6) acts through the perforations in the pickerpads and causes the chip preforms to adhere thereto. Excess or “lace”dough is removed from the cutter roller 88 and may be recycled if sodesired.

The chip preforms are carried around the lower portion of the transferroller 100 to the nip 181 formed between the transfer roller 100 and thefeed roller 102. At that point, overpressure created within thecross-hatched portion of the transfer roller drum 108 facilitatestransfer of the chip preforms from the pick-up and transfer members 105of the transfer roller 100 to the pick-up and transfer members 107 ofthe feed roller 102. The chip preforms are then carried by the members107 around the upper portion of the feed roller 102 and down to thepoint 183 where the feed roller and drum fryer 12 converge. At thispoint, overpressure in the cross-hatched portion of the feed roller drum110 (FIGS. 5 and 6) positively transfers the chip preforms onto thefrying mold elements 26 of the fryer drum 12. The chip preforms are thencooked by being transported through hot oil in the tank 14—specifically,hot oil contained within the space between the outer ring 22 of the drum12 and the inside surface 17 of the housing (see FIG. 2A), whichpreferably is on the order of just one inch wide.

The temperature of the oil and the dwell time of the chips within theoil (determined by the size of the drum 12 and its rate of rotation) arecontrolled for the specific dough being used so that the chips areproperly cooked (e.g., have a desired moisture content) by the time theyhave been carried around the drum to the nip 185 formed between theouter ring 22 of the fryer drum and the take-off roller 150. At thatpoint, the pick-up and transfer members 152 of the take-off roller 150lift the now-cooked snack food chips off of the mold surfaces of thefrying mold elements 26 (by virtue of suction within the take-off rollerdrum), and the take-off roller transports the now-cooked snack foodchips from the bottom portion of the roller to the top portion of theroller.

As shown in detail in FIG. 10, the pick-up and transfer elements 152 ofthe take-off roller 150 pass between the fingers 162 of the take-awayconveyor assembly 160, with the edges of the snack food chips overlyingthe edges of the finger conveyors 162. As the pick-up and transfermembers 152 rotate down and away from the snack food chips, the chipswill be supported by the finger conveyors 162 and are transporteddownstream, away from the fryer apparatus, for subsequent processingsuch as seasoning and packaging.

Although the invention has been described in some detail, it will beapparent to those having skill in the art that numerous modificationsand revisions to the embodiments disclosed herein may be made. Forexample, other types of snack food chips such as tortilla chips may bemade using the invention, and snack food chips made according to theinvention do not necessarily have to be oval and/or saddle-shaped. Forexample, it is contemplated that round snack food chips, rectangularsnack food chips, or triangular snack food chips (such as tortillachips) can be made using the apparatus and methodology of the invention,and it is also contemplated that the specific curvature of chips madeusing the invention can be varied. For example, single-curve chips canbe made, or chips can be made which are multiply curved about axes thatare parallel to each other. These and other such modifications aredeemed to be within the scope of the following claims.

We claim:
 1. A frying mold element for use in frying snack food piecepreforms to make cooked snack food pieces, said frying mold elementcomprising: a stem portion configured to permit air to passtherethrough; and a mold portion attached to said stem portion, saidmold portion having a perforated, open mold surface through whichsuction forces can act to draw a snack food piece preform thereagainst,said mold surface having a predetermined surface contour which is to beimparted to the snack food piece preforms, wherein said mold surface hasa series of grooves or channels formed therein, said grooves or channelsbeing sufficiently dimensioned to permit a cooking medium to circulatetherethrough, whereby the cooking medium is able to pass between saidmold surface and a snack food piece preform held thereagainst.
 2. Thefrying mold element of claim 1, wherein said mold surface is curvedabout a single axis of curvature.
 3. The frying mold element of claim 1,wherein said mold surface is curved about a plurality of axes ofcurvature.
 4. The frying mold element of claim 3, wherein said moldsurface is convexly curved about a first axis of curvature and concavelycurved about another axis of curvature parallel to the first axis ofcurvature such that said mold surface is saddle-shaped.
 5. The fryingmold element of claim 1, wherein said grooves or channels are configuredto facilitate removal of the cooked snack food pieces therefrom.
 6. Thefrying mold element of claim 1, wherein said grooves or channels areconfigured to produce ridged or sinusoidally wavy snack food pieces. 7.The frying mold element of claim 1, wherein said mold portion is adaptedto be carried on a carrier structure for effecting movement of thefrying mold portion through a snack food cooking apparatus and whereinsaid stem portion is constructed and arranged to be secured to saidcarrier structure and said mold portion is constructed and arranged soas to permit said mold portion to be removable with respect to saidcarrier structure.
 8. The frying mold element of claim 7, said stemportion being insertable within an aperture formed in said carrierstructure and including a pair of retention fingers for releasablyengaging an edge of the aperture to releasably secure said stem portionwithin the aperture.
 9. The frying mold element of claim 7, the stemportion being insertable within an aperture formed in said carrierstructure and including a positioning tab for positioning said moldportion in a desired orientation with respect to said carrier structure.10. The frying mold element of claim 7, wherein said stem portionincludes a pair of spring release fingers for engaging apertures formedin a side wall of said mold portion for releasably securing said moldportion to said stem portion.
 11. The frying mold element of claim 7wherein said stem portion and said mold portion are fabricated from ametal selected from the group consisting of stainless steel andaluminum.
 12. The frying mold element of claim 7, wherein said moldportion includes an ion conversion coating.